IEEE802.11ac is a branch of the IEEE802.11 protocol series and introduces a very-high-throughput probing mechanism, which is a channel detection mechanism between a beamformer and a beamformee. With this mechanism, the beamformer is capable of better knowing the situation of a channel between the beamformer and the beamformee. As such, the communication status can be improved by adjusting related parameters. In general, on a network constructed of a basic service set (BSS, Basic Service Set), the corresponding physical device of the Beamformer is an access point (AP, Access point) and that of the Beamformee is a station (STA, Station); and on a network that is not constructed of a basic service set, the corresponding physical device of the Beamformer may be a certain STA and that of the Beamformee may be another STA.
In the prior art, to prevent abnormal situations, IEEE802.11ac specifies that the number of actual active antennas of the beamformee must be larger than or equal to the number of columns (NC) set by the beamformer in a null data packet announcement (NDPA, Null data packet Announcement) message. Therefore, after receiving the NDPA message, the beamformee has no corresponding processing mechanism if it finds that the number of its actual active antennas is smaller than the number of columns set by the beamformer in the NDPA message. This leads to logical imprecision and disorder of IEEE802.11ac, finally affecting the design of related products.